The present invention relates to high quality audio and, more particularly, a wireless speaker system for reproducing high quality multichannel audio.
A home theater system typically comprises one or more signal sources, such as a digital versatile disc (DVD) player, a BLU-ray™ disc (BD) player or broadcast receiver; a display unit; an audio video control receiver (AVR); and multiple speaker units. An audio processor which may be integrated in the AVR or located elsewhere in the system converts analog or digital signals received from the signal source to an appropriate form for transmission to the speaker units. A home theater system may employ wired connections between the audio processor and the speaker units in which analog signals, which may be converted by an audio processor from digital data received from the signal source, are commonly amplified by the AVR and transmitted to the speaker units. However, it can be difficult or impractical to route wires to remote speakers once a room has been finished and the wires can be unsightly and subject to damage when exposed along a wall or routed under a carpet. For this reason, home theater systems often utilize wireless signal paths between the AVR and the speaker units. Digital data, including converted analog signals from a signal source, are packetized and multiplexed into a transport data stream by the audio processor of the AVR. An AVR transceiver modulates a carrier with the transport data stream and transmits the modulated carrier to a transceiver located in each wireless speaker unit making up the system. In the speaker unit, the digital audio data is separated from the carrier and converted to an analog signal or a succession of pulses which are amplified and transmitted to the speaker.
Surround sound, a technique for enhancing the perception of the spatial origin of sound by adding audio channels which are selectively output by speakers that, at least partially, encircle the listener is a common feature of home theater systems. Six channel surround sound audio; exemplified by Dolby Digital®, Dolby Pro Logic II™, DTS™, and SDDS™ surround sound audio; is the standard surround sound audio component of digital broadcast and music and the most common surround sound system for both commercial and home theaters. Six channel surround sound audio systems, known as 5.1 (“five point one”) surround sound systems, utilize five full bandwidth channels; a front left channel, a front right channel, a center channel, and, respective, left and right surround channels; each reproduced by a corresponding speaker. In addition, the 5.1 surround sound system includes one low-frequency effects channel, the point one (0.1) channel, which is reproduced by a subwoofer. Increasingly, manufacturers of home theater systems are adapting an eight channel (7.1) surround audio system with a standard front or center speaker, a subwoofer and four surround speakers. Whereas a 5.1 surround sound system combines both surround and rear channel audio into two channels, a 7.1 surround system splits the surround and rear channel audio into four distinct signals with sound effects directed to left and right channels through speakers to the sides of the listener plus two rear surround channels to the listener's left-rear and right-rear. High end home theater systems, such as 11.1 surround sound systems, with even greater numbers of speakers are contemplated. While wireless digital communication between the AVR and the speakers eliminates problems relating to routing wires, it typically increases the cost of the system because each remote speaker unit must have its own power supply, transceiver to receive the radio frequency signal from the AVR; digital-to-analog converter (DAC) to accurately convert the digital audio signals transmitted by the AVR to an analog signal or a high frequency sequence of pulses and, to provide a signal to drive the speaker, an amplifier to amplify the analog signal or pulses.
What is desired therefore, is an economical wireless speaker unit which produces high quality audio.